A network based on UPnP™ (hereinafter, it is referred to as UPnP for short.) proposed for home networking, comprises a plurality of UPnP devices, services, and control points. A service on a UPnP network represents a small control unit executed within a device, which is an application modeled by state variables. A CP (Control Point) on a UPnP network represents a control application equipped with functions for detecting and controlling other devices and/or services. A CP can be operated on an arbitrary device, the device being a physical device such as a PDA providing a user with a convenient interface. A CP can also constitute a single device together with another service, e.g., a renderer service which expresses images by rendering media data. Therefore, multiple CPs can exist on a UPnP network and the user can control operations on a desired service by choosing a convenient CP depending on his/her current location or employed device.
Once a home network as above is built in a particular place such as a home, the user can conveniently make use of desired operations (e.g., operations of duplicating or transferring data between separate devices) irrespective of his/her current location; moreover, multiple users can share the same device at the same time, in the same place.
As described above, when multiple users use networked devices simultaneously or sequentially, or multiple tasks are carried out on networked devices simultaneously or sequentially, required quantity of data transmission may exceed transmission bandwidth provided by a network. In this case, network access for data transmission should be restricted, which such restriction should be decided based on priority of the corresponding transmission. Therefore, a service is necessary, which can determine priority of access when the access is requested on a network. In addition, more than one such service can exist on the network.